In Situ Fourier Transform Infrared Investigation on the Low-Level Carbon Dioxide Conversion over a Nickel/Titanium Dioxide Catalyst

Efficiently converting atmospheric carbon dioxide (CO2) is crucial for sustainable human development. In this study, we conducted systematic in situ Fourier transform infrared tests to examine how hydrogen (H2) partial pressure affects the conversion of low-level CO2 (around 400 ppm) using nickel/titanium dioxide (Ni/TiO2). Results show that increasing H2 partial pressure significantly increases surface monodentate formate species, leading to enhanced methane (CH4) production at both 250 and 400 °C. Conversely, on Ni's surface, the key species are formyls and bidentate formate at 250 °C, but these decrease significantly at 400 °C. These findings indicate that low-level CO2 is more easily converted to CH4 over Ni/TiO2 than Ni, regardless of temperature. Additionally, the strong Ni–TiO2 interaction gives Ni/TiO2 an advantage in converting low CO2 concentrations, with excellent durability even at 400 °C. This study enhances our understanding of direct CO2 conversion and aids in the development of advanced CO2 emission reduction technologies.